But i think that those Category IDs to install appx and appxbundle, only works if one have .xml file that points to license file... (Only Available on VLSC, that have Windows 10 Inbox Apps ISO, or Microsoft Store from Business. Both will require corporate account enrolled with IT department)

This may be useful to improve Add-Store-Dynamic script and add lacking files, such as Desktop App Installer, StorePurchase App and XboxIdentity Provider.

Edit: to clarify, I was able to successfully get store working on LTSC 2019, but I'm attempting to get a free game from the store, and the store requires an update from 1809 to 1909 apparently, May update. Any idea if there is a package that can do that or give it the requisite files to run?

Alright, sorry, my bad. I thought all Enterprise versions don't have Store bundled, but obviously "Enterprise versions of normal Windows 10" do have Store So I tried on LTSB, LTSC and Server, and here is my testing result:
1. On LTSC 2019: Add-Store-Dynamic worked, I didn't try other methods.

2. LTSB: Also tried old packages 2019-07-16 and 2017-11-11.
2a. If Store can work after doing these initial steps, it is very likely that it would work later: try disabling Store's Auto-update function right after installation, then install a small-sized and supporting old Windows 10 version such as Calculator+ HD.

2b. Without disabling Store's Auto-update function: If you open Store and don't do something immediately, the Auto-update function may kick in and try to update Store itself and App Installer. The latter always fail which would lead to the situation: when you try downloading other app, the download status would change from "Checking product files" to "Calculating download size", "Almost ready", and it would stuck at "Downloading..." for some long time without showing download speed (which would make you think things don't work, just like I did). However, at least in my case, it still works! But a 50MB app (Calc Pro HD Free) took an hour to complete. But again, after that, downloading apps work normally and the download progress box would show normal download speed.

Note: Instead of App Installer, if you try to download a troubling app such as Messenger (eventhough it says that it supports old Windows 10 version 10240.0!), you will get errors and it will cause the same situation.

3. Server 2016 (Version 2018-02): Also tried old packages 2019-07-16 and 2017-11-11.
Nothing worked. The errors were "Something happened on our end", or clicking "Install/Get" button was like clicking a greyed-out button.

Sorry im a complete noob when it comes to things like this, but yeah it wont let me install the xbox beta app because i dont have the latest version of windows, it tries to update windows for me but says it wont install because im using enterprise. ive been able to install games before, last time i had it working was last year but im not really sure how to get it working again now. i can still launch games that i had installed already but trying to install any other game wont work if its through the xbox pass